[GitHub] nifi pull request #2007: NIFI-4184: PutHDFS Processor Expression language TR...

[ijokarumawak <gi...@git.apache.org>]

Github user ijokarumawak commented on a diff in the pull request:

    https://github.com/apache/nifi/pull/2007#discussion_r128689940
  
    --- Diff: nifi-nar-bundles/nifi-hadoop-bundle/nifi-hdfs-processors/src/main/java/org/apache/nifi/processors/hadoop/PutHDFS.java ---
    @@ -386,11 +388,14 @@ public void process(InputStream in) throws IOException {
             });
         }
     
    -    protected void changeOwner(final ProcessContext context, final FileSystem hdfs, final Path name) {
    +    protected void changeOwner(final ProcessContext context, final FileSystem hdfs, final Path name, final FlowFile flowFile) {
             try {
                 // Change owner and group of file if configured to do so
    -            String owner = context.getProperty(REMOTE_OWNER).getValue();
    -            String group = context.getProperty(REMOTE_GROUP).getValue();
    +//            String owner = context.getProperty(REMOTE_OWNER).getValue();
    +//            String group = context.getProperty(REMOTE_GROUP).getValue();
    +            String owner = context.getProperty(REMOTE_OWNER).evaluateAttributeExpressions(flowFile).getValue();
    +            String group = context.getProperty(REMOTE_GROUP).evaluateAttributeExpressions(flowFile).getValue();
    +
                 if (owner != null || group != null) {
    --- End diff --
    
    When I tested with an expression that returns no value, e.g. specify an attribute name which does not exist, then the group string became an Empty string. And the file was updated with an empty group. To avoid that, Could you add following code before this if statement? to make empty string into null:
    
    ```
                owner = owner == null || owner.isEmpty() ? null : owner;
                group = group == null || group.isEmpty() ? null : group;
    ```
    
    ![image](https://user-images.githubusercontent.com/1107620/28451433-3b1718a2-6e28-11e7-9473-282bbfcdd881.png)



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